(1) باب صَلاَةِ الْمُسَافِرِينَ وَقَصْرِهَا
Anas reported:
The Messenger of Allah (ﷺ) said four rak'ahs in the noon prayer while at Medina, but he offered two rak'ahs in the afternoon prayer at Dhu'l-Hulaifa. (ID)
Reference (ID): Sahih Muslim 690 a (ID)
In-book reference (ID): Book 6, Hadith 12 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1469 (ID)